306 



C. TSHIKAWA. 



of it are irregular in outline. The chromosomes have now 

 distinctly divided into two portions radinting from the pole of the 

 nucleus wliere the arclioplasms lie. Eîich chromosome consisting of 

 a number of microsomes arranged like bends, is bent ii|)on itseli', 

 as is so usiimI iu this stage of karyokinesis in other ;inim;ils. The 

 number of tliese chi-omosomes, ns stated above, is very difficult to 

 ascertain. The most interesting phenomenon in this tigure (o/)) is 

 the spindle fibres, of which there are two kinds ; those, whicli I call 

 CENTRAL FiBHES (Figs. 35, 8(j, 37, 4>>, cf.), ^y'"o imbedded in the 

 concavity found in the wall of the nucleus, and standing in no direct 

 relation with the nucleoplasm ; and those (Figs. 35, 3^, 37, 4(S, 

 rf.') which are seen at the side of tlie central fibres, riuming from 

 the centre of an archoplasm to the bent ends of the cliromosomes, 

 and which I will call the radiating fibres. Where they join the 

 nuclear wall, the latter appears (piite indistinct, but whether they 

 pass through the wall of the nucleus at these points and are dii-ectly 

 attached to tlie chromosomes can not be made out. In Fig. 37, 

 which represents a section of a dividing nucleus at about the same 

 stage as Figs. 35, 36, and 37, a homogeneous mass of nucleoplasm 

 is found ;it the poles of the nucleus, external to the bent ends of \}\q 

 chromosomes. In this mass of nucleoplasm, wln'ch is easily distin- 

 guished from the more granular archoplasm lying outside, ar(i seen 

 many parallel fibres running in the same direction as the radiating 

 fibres of the archoplasm represented in Figs. 35, 30, and 4(S, but 

 unfoitunatelv not to be seen in the series of sections represented by 

 Fig. 37. We shall come to this again in the part devoted to general 

 considerations, as further discussion of the subject is beyond the region 

 of observation. 



WIhmi the division has proceeded as far as Fig. 35 or 3(5, the 

 median poi'tion of the archoplasmic spindle is swollen up a little, as 



